Question: The sum of $3$ consecutive odd numbers is $39$. What is the third number in this sequence?
Explanation: Call the first number in the sequence $x$ The next odd number in the sequence is $x + 2$ The sum of the $3$ consecutive odd numbers is: $x+ (x + 2)+ (x + 4) = 39$ $3x + 6= 39$ $3x = 33$ $x = 11$ Since $x$ is the first number, $x + 4$ is the third odd number. Thus, the third number in the sequence is $15$.